Concrete Slab Foundation - Process & Best Practices

we're talking today about slab on grade concrete foundations I'm standing on a concrete slab which is going to become a collectors garage we're working with MF architecture here and this 10 car collectors garage has a guest house above you can follow this project on my twitter and instagram accounts as hash tag Auto house but let's actually back up two weeks ago as we were just starting to lay the rebar and I'm gonna walk you through the steps of building this concrete slab on grade project by far the most common type of foundation here in the south is slab on grade and there's really two varieties of that there's post-tension slabs that's where you have a cable that runs through the slab there's not rebar in there and those cables are tensioned at the outside of the slab edges later so the slab is in compression that's not my favorite type of foundation what we're doing here today is I think the best type of slab on grade this is a steel reinforced slab let me back up a minute and tell you how we got to where we are today the first step after we've designed the architecture is to get a structural engineer involved the structural engineer is gonna hire a geotechnical engineer who's gonna actually do a boring in the soil here and tell us what kind of ground is underneath us now if we're on rock we're in really good shape there's not a lot of additional steps for reinforcement needed but in this case our soil below us had a high plasticity index meaning there was some clay soil that may experience some up-and-down movement on this house in the future so we had to design a very stiff slab that would resist that soil movement the yellow plastic you see behind me is the vapor barrier for this house this is called stego wrap this comes in a 10 and a 15 mil variety and I really like this for the vapor barrier the vapor barrier is important because any moisture that's in the soil we want to make sure that's kept off of the slab as much as possible so this vapor barrier is doing that job for us this one is particularly tough and durable and then make a great seam tape which is this red tape here so as we overlap that we can really make sure that moisture is not going to make its way to it to the slab so now when you look at that yellow vapor barrier there you can see that there's channels cut in a grid pattern through that those channels are what is gonna add the stiffness to the slab ultimately those are gonna get filled with a grid pattern of both rebar and and that grid is gonna make this super stiff slab so that now as my soil exerts pressure on one part of the slab the whole slab is gonna move as one unit just like a boat rocking on the Seas that's really the best type of slab on grade especially if you've got bad soil after the rebar has been placed and tied I want to give you a couple of other special details we did we used a fine wire mesh on top of all that rebar similar to what you'd use if you were pouring a driveway and that fine mesh really locks around the concrete and prevents those little cracks that you see often on concrete slabs you'll also notice on all the plumbing pipes and anywhere we had a corner or an angle on this foundation we laid some rebar on a 45 degree angle that's going to help prevent those cracks from happening at those locations and finally where the plumbing penetrations are in the slab we've wrapped those with a terming mesh that's a fine stainless steel mesh which prevents the termites from tunneling up at those locations that's a lifetime termite treatment for a house like this okay so next pour day that is a really fun day to watch we had about a dozen concrete guys from booth concrete out here they did a great job placing the slab we had a hundred yards of concrete we had a boom truck it was really a fun day you also notice on the outside of the slab we have hold downs those are called Jay bolts and those are placed during the concrete pour we also have several in bed plates on this project there's a lot of red iron to take a massive cantilever that's happening on this project and those also need to be placed just prior to finishing this lab after all that's done we came in and power trout the entire slab you get the perfect finish we were looking for and then at the end of the day before we wrapped up we covered the entire slab with some black plastic that's going to prevent that evaporation from happening too quickly and it's really going to give us that fine finish with as few cracks as possible now this is wintertime conditions so we could really just cover this for five or six days and not have to do anything else but if it was summertime we'd really want to flood this slab on a continual basis either with an intermittent sprinkler or with a guy in a hose for at least four or five maybe even a week's time to make sure this slab really has all the water it needs and gives us that fine finish we're looking for a for more best practices on slide jobs or foundations in general check out my other playlists on YouTube here otherwise follow me on Twitter Instagram we're gonna hash tag this project Auto house we'll see you next time

Channel: Matt Risinger

Views: 792,885

Rating: 4.8494201 out of 5

Keywords: slab, concrete slab, slab foundation, slab vs piers, concrete foundation, concrete, concrete best practice, slab on grade

Id: stOvOxIDRYo

Length: 5min 25sec (325 seconds)

Published: Fri Apr 29 2016